Inter-seasonal variation in nitrogen uptake rates of the eutrophic Cochin estuary and adjacent coastal Arabian Sea

Bhavya Panthalil; Sanjeev Kumar; G V M Gupta; Sudheesh Valliyodan; Jabir Thajudeen

doi:10.1016/j.marpolbul.2023.115310

Inter-seasonal variation in nitrogen uptake rates of the eutrophic Cochin estuary and adjacent coastal Arabian Sea

Mar Pollut Bull. 2023 Sep;194(Pt B):115310. doi: 10.1016/j.marpolbul.2023.115310. Epub 2023 Aug 3.

Authors

Bhavya Panthalil¹, Sanjeev Kumar², G V M Gupta³, Sudheesh Valliyodan³, Jabir Thajudeen⁴

Affiliations

¹ Physical Research Laboratory, Ahmedabad, India. Electronic address: bhavya@iisertvm.ac.in.
² Physical Research Laboratory, Ahmedabad, India. Electronic address: sanjeev@prl.res.in.
³ Centre for Marine Living Resources and Ecology, Cochin, India.
⁴ Cochin University of Science and Technology, Cochin, India.

PMID: 37542927
DOI: 10.1016/j.marpolbul.2023.115310

Abstract

The study assessed the Cochin estuary and adjacent coastal Arabian Sea for their seasonal variation in nitrate (NO₃^-) and ammonium (NH₄⁺) uptake rates by total and nano + picoplankton using the ¹⁵N tracer technique. The results suggested that the NO₃^- and NH₄⁺ uptake rates in the Cochin estuary are higher than those in the adjacent coastal Arabian Sea. NO₃^- and NH₄⁺ uptake rates in the nearshore stations in the off Cochin station were high, indicating the influence of the eutrophic estuary. NO₃^- and NH₄⁺ uptake rates conducted in off Mangalore transect were significantly lower than those of the off Cochin as it does not have an exchange with eutrophic systems. The nano + picoplankton's contribution to the total DIN uptake rates in the Cochin estuary was 77-98 %, indicating the relevance of nano + pico phytoplankton in the N cycling of the region.

Keywords: Coastal pollution; Estuarine-coastal coupled systems; Nanoplankton; Nitrogen budget; Upwelling.

MeSH terms

Estuaries*
Nitrates / analysis
Nitrogen* / analysis
Phytoplankton
Seasons

Substances

Nitrogen
Nitrates